Roster battles: the fight card

One preseason game left. Sixty minutes of football. Twenty-two players to be cut within five days. The mathematics of the NFL summer makes for some interesting mini-dramas this time of year.

Coach Mike Singletary said he and his staff have “a decent idea” of what their ultimate 53-man roster will look like. But he admitted the final preseason game, Thursday against San Diego, could help settle a few spots. These are among the most contested:

Brit Miller vs. Jehuu CaulcrickYou figure Frank Gore, Brian Westbrook and Anthony Dixon are safe among the halfbacks. Michael Robinson is needed for special teams, and Moran Norris is the guy at fullback. The 49ers could stop the backfield there, or they could go with a second fullback. Either of these two could play a bunch of special teams, though Miller is a little more polished. Caulcrick, on the other hand, can carry the ball in a pinch.Projected winner: Miller

Jason Hill vs. Kyle WilliamsCount Michael Crabtree, Josh Morgan, Ted Ginn and camp sensation Dominique Zeigler against your books. The next slot could match Hill, a fourth-year veteran who has operated on the periphery of the offense, and Williams, a rookie who can also return kicks. Williams looked to have the edge before he sprained his toe, an injury that probably will keep him out of the next game.Projected winners: both

Barry Sims vs. Alex Boone vs. Adam Snyder vs. Tony WraggeOK, walk through the O-line with me: Joe Staley, Mike Iupati, Eric Heitmann, Chilo Rachal and Anthony Davis are the true starters. David Baas should be the center while Heitmann rehabs his broken fibula. Things are wide open after that. Snyder has the most versatility; he can play up and down the line. Wragge is smart and can snap the ball. Sims is the guy NFL teams are always trying to replace, but he proves just valuable enough to keep around. Boone is the up-and-coming tackle, a giant who has yet to tap his potential.Projected winners: Snyder, Wragge and Boone

Demetric Evans vs. Khalif MitchellDefensive line is one of the 49ers’ thinnest units. Justin Smith, Isaac Sopoaga and Aubrayo Franklin are locks. You’d have to figure on Ray McDonald and Ricky Jean Francois, too. It’s conceivable the Niners would stop there, but that isn’t much of a rotation. If they keep two more D-linemen, it will probably be Evans and Mitchell. If they keep one, the ninth-year vet and the kid from East Carolina will be going toe to toe.Projected winner: Evans

Diyral Briggs vs. Travis LaBoyThere was a lot of transition at linebacker during training camp, and one or both of these two could be the winner(s). Briggs had an excellent camp, and has fared pretty well in preseason games. LaBoy has been better than OK in exhibition games; he’s been a terror, including his knockout of Raiders QB Jason Campbell on Saturday. Patrick Willis, Takeo Spikes, Parys Haralson, Manny Lawson and NaVorro Bowman are set at LB. Ahmad Brooks will be there unless his kidney injury is worse than everyone thinks. Matt Wilhelm knows the defense and is a core special-teamer; I’m saying he’s in. That’s seven, and the 49ers haven’t kept more than eight since 2003. Do they go with youth or experience? With pass rush or all-around play? For how much does special-teams ability count? We’ll see.Projected winner: Briggs

Phillip Adams vs. Karl Paymah vs. Will James vs. Curtis TaylorThe secondary almost certainly will include Nate Clements, Shawntae Spencer, Tarell Brown, Michael Lewis, Dashon Goldson, Reggie Smith and Taylor Mays. That’s the bare minimum of coverage. The 49ers would seem to need more depth at cornerback, and at one point Will James was coming on strong. Now he’s on the shelf with an ankle injury, perhaps opening up a door for Adams or Paymah. Or would SF keep two of those cover men and say goodbye to Taylor? One thing favoring Adams and Taylor: big special-teams contributions.Projected winners: Adams, Taylor